Résumé
Grape vines are one of the few crops in the world that is cropped only as a pure crop system. Vineyards face severe environmental concerns such as soil degradation, heavy loads of pesticides and pests attacks. In Roman times, vineyard cultivation was performed as an agroforestry system called Arbustra, with vines growing on living trees used as trellises. Scattered trees such as peach, almond or olive trees were also grown in vineyards in Europe until recently. These trees have been destroyed to allow easy mechanisation of the vineyard management, including mechanical harvesting of grapes. New vineyard agroforestry plots were set up in 1996 in the south of France, and have been monitored since then for grape production and tree growth. Various tree species were introduced into vineyards, at a density of 222 trees/ha, on shallow rocky soils prone to drought. Both evergreen resinous and broadleaved deciduous tree species were introduced, with Sorbus domestica (Service tree) and Pinus pinea (Stone pine) as the key species. Control plots with pure tree and pure vine plantation were available. After 12 years of cultivation, grape production and tree growth data showed that vineyard agroforestry is possible. Tree growth is enhanced in the agroforestry system, and grape production is not yet reduced by tree competition, except on extremely shallow soils. Competition for water and/or nutrients appears to be the main limiting factor, while light competition seems not to be a problem so far. Root pruning with a sub-soiler was used to limit water competition by the trees on the vines and proved useful. Some preliminary assessments of pest predators in the vineyard system show that mite control may be enhanced by the presence of trees in vineyards. This could allow a reduction in the use of pesticides in vineyards, but more detailed studies are needed to con!rm this hypothesis